University of Canterbury Professor Katie Pickles said memories of the pre-quake Christchurch were fast fading as more of the city's iconic buildings and landmarks were demolished.

"Many Christchurch landmarks have been demolished to make way for new buildings in what is becoming an exciting city," she said.

"But we have never been a demolition city before, with hard hats, high-viz, cranes, and wrecking balls. This is what Cantabrians see and hear on a daily basis. Memories of the past pre-quake city are fading.'"

Pickles will discuss lost landmarks as a key speaker at the second annual Seismics and the City forum at the Addington Events Centre on Thursday.

The University of Canterbury's new Quake Centre will also be launched that day at the Westpac Hub.

Pickles said memories and emotions were tied to particular places, and if the places were demolished, they could no longer act as memory triggers.

The iconic and landmark buildings demolished since Canterbury's earthquakes would still be available as images in books and galleries, but would be "locked inside our heads without the triggers to escape".

"We all make 'mental maps' in our heads made up of our life journeys around our environment. The earthquakes have short-circuited these mental maps"

Different buildings and places held different memories for different people, but it was our individual mental maps that added up to make history, she said.